Chromosols are soils that display a strong texture contrast between surface (A) horizons and subsoil (B) horizons. The upper part of the subsoil ranges from slightly acid to alkaline (pH >5.5) but is not sodic. Using the Australian Soil Classification, Chromosols can be grouped further (in to Suborders) based on the colour of the upper 20 cm of the subsoil (i.e. Red, Brown, Yellow, Grey and Black). These can be further differentiated based on subsoil characteristics (in to Great Groups) such as the nutrient level capacities and ratios and the presence of carbonate or lime.
Chromosols occur throughout the region and can be found on the alluvial Riverine Plains and the uplands where the dominant occurrences are north, east and west (sporadic occurrences) of Benalla, east of Seymour and the Mansfield area. Surface soil textures and depth vary considerably and have significant implications for management; affecting soil workability, permeability, crop establishment, moisture availability and erodibility. The subsoils of the Brown, Yellow and Grey variants are often mottled. However, this is not the case for some Brown Chromosols on alluvial flats which are friable, where drainage is not restricted.
The Red Chromosols are the most permeable of the Chromosols in the region and tend to be in the slightly higher and thus better drained topographic positions, compared to their Brown, Yellow and Grey counterparts. Although in the case of the Mansfield area, subsoil colour is derived from the lithology (i.e. Carboniferous red beds).
Red Chromosol on Hills near Dookie.
|Chromosols in the Goulburn Broken Region|
This broad scale map presents an overview and should only be used as a general indication of the distribution of Chromosols in the Goulburn Broken Region. It shows areas where Chromosols are most likely to occur within the region. Note that other soil types may also occur within these mapped areas (although they are likely to be a more minor component).
This map has been developed from work done by DPI's former Centre for Land Protection Research as part of the Goulburn Broken Dryland Regional Development Project. This work utilised existing surveys, remote sensing information and some additional field work to develop an updated 1:100 000 soil/landform coverage across the region.
Chromosols in the Goulburn Broken Region
Soils are difficult to map at this broad scale because of their diversity. Even in relatively small areas, a number of soils may occur which relate to differences in topography and landscape position. Variation in some of the major soil profile properties can also occur within these mapped areas. Any agricultural enterprise should be based on a proper on-site assessment of the soil and landscape.
A number of soil surveys have been completed in this region at varying scales and intensity. However, in some areas very little soil survey has taken place (refer to the Soil and Land Survey Directory).